<!DOCTYPE html>
<html lang="en" style="font-size: 20px;">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, user-scalable=no,initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <title>Document</title>
    <script type="text/javascript" src="JS/set_root.js"></script>
    <style type="text/css">
        body{
            margin: 0px;
        }
        .header{
            height: 2.5rem ;
            background-color: gold;
            text-align: center;
            line-height: 2.5rem;
            font-size: 20px;
        }

    </style>
</head>
<body>
    <div class="header">头部文字</div>

</body>
</html>